Make the size of "cb_handle_t" same for 32/64-bit

cb_handle_t is usually created by Surfaceflinger which is a 64-bit process on
64-bit platform, and used by client processes which could be 32-bit processes
or 64-bit processes. Since the "cb_handle_t" is like a protocol, we should make
its size same for both 32-bit and 64-bit processes.

Change-Id: I11011576a389db2662888abfaf62dfb8e5611b7c
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
diff --git a/system/OpenglSystemCommon/gralloc_cb.h b/system/OpenglSystemCommon/gralloc_cb.h
index c138964..a0f6ed8 100644
--- a/system/OpenglSystemCommon/gralloc_cb.h
+++ b/system/OpenglSystemCommon/gralloc_cb.h
@@ -96,7 +96,11 @@
     int glType;             // OpenGL type enum used when uploading to host
     int ashmemSize;         // ashmem region size for the buffer (0 unless is HW_FB buffer or
                             //                                    s/w access is needed)
-    intptr_t ashmemBase;         // CPU address of the mapped ashmem region
+    union {
+        intptr_t ashmemBase;    // CPU address of the mapped ashmem region
+        uint64_t padding;       // enforce same size on 32-bit/64-bit
+    } __attribute__((aligned(8)));
+
     int ashmemBasePid;      // process id which mapped the ashmem region
     int mappedPid;          // process id which succeeded gralloc_register call
     int lockedLeft;         // region of buffer locked for s/w write